1. Field of the Invention
Broadly, the present invention provides a closure apparatus for an inclined duct. In a more specific embodiment of the invention there is provided a closure for such a duct which is utilized for the transfer of fuel elements into and out of a nuclear reactor vessel.
2. Description of the Prior Art
In a typical liquid metal cooled breeder reactor, two vessels are utilized. One vessel houses the reactor core and associated components. The other vessel is utilized for storage of fuel elements. Generally, each of the two vessels will be interconnected via inclined ducts to a fuel transfer cell which moves the fuel elements between the two vessels via the inclined ducts. The duct leading into the reactor-containing vessel is subject to extreme temperatures and radiation during normal operation of the reactor. Thus, the closure for that duct must provide for both thermal insulation and radiation absorption. To accomplish this result, the plug portion of the closure will generally have substantially the same configuration as the duct in cross-section and have sufficient length to achieve the required degree of thermal insulation and radiation absorption. The removal and insertion of such plugs requires a mechanism capable of tilting a sufficient amount to achieve axial alignment with the open end of the duct and must be sufficiently strong to support the plug while moving it axially in an inclined direction corresponding to that of the duct. Obviously, such a mechanism is necessarily bulky and complex. Accordingly, there is need for a closure for such a duct which could be raised and lowered in a vertical direction by a hoist to simplify its insertion and removal from the duct.